Cable spacers for electrical overhead transmission lines

ABSTRACT

A device for spacing electrical conductors which are used in high voltage transmission lines. The device includes a central hub provided with two or more cavities. A rigid arm articulately extends into each cavity. The arm is provided at one end with a truncated double cone or knob-like structure and the other end is provided with means for holding the conductor. Interposed between the inside walls of the cavity and the knob of the rigid arm, within each cavity, is an elastomeric sleeve having a substantially circumferentially continuous groove arranged adjacent to and alongside of the intersection of the two cones which comprise the knob.

United States Patent [191 Schiavone 1 CABLE SPACERS FOR ELECTRICALOVERHEAD TRANSMISSION LINES [75] Inventor: Donald James Schiavone,Huron,

Ohio

[73] Assignee: Gould Inc.

[22] Filed: March 31, 1972 [21] Appl. No.: 240,116

[52] U.S. Cl. ...l74/40 R, 174/146 [5 1] Int. Cl. ..H02g 7/12 [58] Fieldof Search ..l74/40 R, 42, 146

[56] References Cited UNITED STATES PATENTS Torr ..l74/l46 X Jan. 16,1973 [57] ABSTRACT A device for spacing electrical conductors which areused in high voltage transmission lines. The device includes a centralhub provided with two or more cavities. A rigid arm articulately extendsinto each cavity. The arm is provided at one end with a truncated doublecone or knob-like structure and the other end is provided with means forholding the conductor. Interposed between the inside walls of the cavityand the knob of the rigid arm, within each cavity, is an elastomericsleeve having a substantially circumferentially continuous groovearranged adjacent to and alongside of the intersection of the two coneswhich comprise the knob.

4 Claims, 3 Drawing Figures CABLE SPACERS FOR ELECTRICAL OVERHEADTRANSMISSION LINES The invention relates generally to spacer devices forspacing two or more electrical cable conductors in overhead transmissionlines and, more particularly, concerns the manner in which theconductors are resiliently constrained.

Cable spacers of the type herein under consideration are well known inthe art and comprise generally a hub provided with two or more cavitiesfor receiving an articulately disposed rigid arm which in turn has meansarranged remote from the hub to clampingly receive the cable. The armterminates in the cavity with a knob having a truncated double cone-likeconfiguration. lnterposed between the knob and the walls of the cavityis an elastomeric sleeve which resiliently constrains the movement ofthe arm and causes the arm to return to a neutral position after theconditions which have caused such movement have subsided. Generally, themovement of such arms is induced by wind forces which are counteractedby the elastomeric sleeve. A detailed description of such a device canbe found in U. S. Pat. No. 3,157,731.

In devices of the type described above, it has been found that angularmovement of the double truncated cone knob within the cavity has thetendency to place the elastomeric sleeve under shear stress. This causesdisplacementpr so-called slippage, of all or part of the sleeve in theregion defined by the intersection or juncture of the cones along itscircumference, i.e., the location of the maximum diameter of the knob.

The phenomenon of slippage occurs when the elastomeric sleeve issubjected to excessive shear stresses at the critical region orintersection of the double truncated cone. More specifically, a relativemovement between the double truncated cone OD and the correspondingelastomeric sleeve lD results in a permanent slippage displacement. Oncethis slippage has taken place the truncated cone or spacer arm fails toreturn on its own to its original or neutral position, and consequentlyit fails to maintain a constant conductor spacing which is the primefunction of this spacer. Furthermore, a frequent occurrence of this typeof cycling condition, which does occur as a result of wind inducedvibrations, will establish abrasive conditions accelerating the failureof the elastomer due to a conversion and breakdown of the coherentelastomeric material into granular-like substances which are devoid ofthe desired elasticity.

As has been noted above, the spacers are used on overhead transmissionlines. It is thus not feasible to frequently check whether theelastomeric sleeve has deteriorated, without considerable effort andexpenditure.

It is therefore the primary object of the present invention to improvespacing devices of the type described above in which the movement orslipping of the elastomeric sleeve is minimized and the volume of andpressure application upon the elastomeric material in the criticalregion, i.e., in the region adjacent to the juncture of the twotruncated cones forming the knob, is substantially reduced.

lt is a still further object of the present invention to provide aspacer device having a hub provided with a cavity for receiving a rigidarm and in which the elastomeric sleeve interposed between the cavitywalls and the knob has reduced wall thickness areas in the regionadjacent to the juncture of the two cones forming the knob.

An aspect of the present invention resides in the provision of a spacerdevice for the spacing of two or more individual conductors of anoverhead electrical transmission line. The spacer device includes arigid hub formed with a cavity in the periphery thereof with the cavitybeing formed generally with a mirror image of a double truncated cone. Arigid arm extends articulately with one end into this cavity and the armis provided at that end with a knob which has, generally, theconfiguration of a double truncated cone of a shape similar to butsmaller in overall dimension than the inside walls of the cavity. Theoutside surfaces of the knob converge towards the maximum diameter ofthe double cone and at that location merge to establish a curvedjuncture; the axis across the diameter of the juncture extendsperpendicularly to the longitudinal axis of the arm. An elastomericsleeve is interposed between the knob and the walls of the cavity withthe sleeve embracing at least partially the converging surfaces of thesleeve. The internal face of the sleeve has a groove extending along andfacing the circumference of the double cone curved juncture.

Another aspect of the present invention resides in the provision of adevice of the type described in the preceding paragraph in which thegroove of the sleeve is dimensioned in such a manner that the widththereof approximates the curved portion of the juncture region.

A still further aspect of the present invention resides in providing aspacer device of the type referred to above in which the groove of thesleeve is relatively deep and approximates percent of the thickness ofthe sleeve. In order to facilitate assembly, the sleeve may comprise twohalf shells and in the assembled condition the groove iscircumferentially continuous.

For a better understanding of the present invention, together with otherand further objects thereof, reference is had to the followingdescription taken in connection with the accompanying drawings, and itsscope will be pointed out in the appended claims.

In the drawings:

FIG. 1 shows a plan view of a hub and one arm of a spacing device shownpartly in section with the remaining arms being shown partlyfragmentary;

FIG. 2 is a cross-sectional view of the half shell of the elastomericsleeve; and

FIG. 3 is a substantially diagrammatic illustration of the movement ofthe knob relative to the sleeve and the hub; as shown, forsimplification, the elastomeric sleeve is illustrated as not being underpre-compression.

Referring now to the drawings, there is shown a spacing device having ahub 10 composed of two half shells, or discs (not shown) which aresecured together by means of rivets 12. The central hub l0 is providedwith a plurality of cavities 14 in the periphery thereof with eachcavity having, generally, the mirror image of a double truncated cone.The number of cavities will depend upon the application for which theinvention is intended and may range from 2 to usually not more than 12.Each cavity is adapted to receive one end of a rigid spacer arm 16 ofthe type well known in the art. The arm 16 extends articulately into thecavity 14 with a knob 18 having generally the configuration of a doubletruncated cone of a shape similar to but smaller in overall dimensionthan the cavity 14. The outside surfaces of the knob 18, see 180 and 18bof FIG. 3, converge towards the maximum diameter of the double cone, see180. This is the location where the generally flat surfaces 180 and 18bmerge in such a manner so as to establish a curved juncture 20. In otherwords, the region 20 of the curved junction is in the location definedby the intersection between each cone, of the double cone, andencompasses the peripheral area of the knob which is curved. Thisintersection, or the axis across the diameter of the juncture, extendsperpendicularly to the longitudinal axis of the arm 16. The knob isusually adapted to make an angular movement of about degrees from theneutral longitudinal axis.

lnterposed between the knob 18 and the internal walls of the cavity 14is an elastomeric sleeve 22 which embraces,at least partially, theconverging surfaces, or flat sides, 18a and 18b of the knob. The sleeve22, to facilitate assembly, is made of two half shells (not shown) andthe total configuration thereof is similar to a double truncated coneproviding again a mirror image of both the cavity 14 and the knob 18,except that the axial ends 24 are open in order to permit articulationof the knob 18 or to avoid interference with such movement.

The internal face of the sleeve 22 is provided with a circumferentiallyextending groove 26 which, in assembled condition within the cavity,extends along and faces the circumference 'of the double cone curvedjuncture or region 20. v

In order to minimize the amount of elastomeric material which isdistended or can cause slippage in the critical region, i.e., in theregion adjacent to curved juncture 20, the width of the groove 26approximates the curved portion of the juncture. It has been found to bedesirable to make the groove 26 as deep as possible. From a practicalpoint of view, the optimal maximum depth appears to be approximately 75percent of the thickness of the sleeve. From an operating point of view,it may be desirable, indeed advantageous, to remove even moreelastomeric material in this critical region; however, for ease ofmanufacture of the part, particularly during the molding operation, itis advantageous to maintain the integrity of the main body of theelastomeric sleeve and therefore a removal of not much more than percentof the material in the grooved region is desirable.

When the two half shells are assembled they provide a substantiallycontinuous groove around the circumference of the knob in juxtapositionor adjacent to the curved juncture.

While a three-cable spacer unit is illustrated in FIG. 1, it is obviousthat the invention is not limited to any number of spacer arms that maybe used with a hub 10.

While there have been described what are at present considered to be thepreferred embodiments of this invention, it will be obvious to thoseskilled in the art that various changes and modifications may be madetherein without departing from the invention, and it is aimed,therefore, in the appended claims to cover all such changes andmodifications as fall within the true spirit and scope of the invention.

hat is claimed is:

l. A spacer device for spacing two or more individual conductors of anoverhead electrical transmission line, comprising:

a rigid hub formed with a cavity in the periphery thereof havinggenerally the mirror image of a double truncated cone;

a rigid arm extending articulately with one end into said cavity andprovided at said end with a knob having generally the configuration of adouble truncated cone of a shape similar to but smaller in overalldimension than said cavity;

the outside surfaces of the knob converging towards the maximum diameterof the double cone and merging, establishing a curved juncture, the axisacross the diameter of the juncture extending perpendicular to thelongitudinal axis of the arm;

and an elastomeric sleeve between said knob and the walls of the cavityembracing at least partially the converging surfaces, said sleeve havinga groove in the internal face extending along and facing thecircumference of the double cone curved juncture.

2. A device according to claim 1, wherein the width of said grooveapproximates the curved portion of the juncture.

3. A device according to claim 1, wherein the depth of said grooveapproximates 75 percent of the thickness of the sleeve.

4. A device according to claim 1, wherein said sleeve comprises two halfshells providing in assembled condition a substantially continuousgroove adjacent to said curved juncture.

1. A spacer device for spacing two or more individual conductors of anoverhead electrical transmission line, comprising: a rigid hub formedwith a cavity in the periphery thereof having generally the mirror imageof a double truncated cone; a rigid arm extending articulately with oneend into said cavity and provided at said end with a knob havinggenerally the configuration of a double truncated cone of a shapesimilar to but smaller in overall dimension than said cavity; theoutside surfaces of the knob converging towards the maximum diameter ofthe double cone and merging, establishing a curved juncture, the axisacross the diameter of the juncture extending perpendicular to thelongitudinal axis of the arm; and an elastomeric sleeve between saidknob and the walls of the cavity embracing at least partially theconverging surfaces, said sleeve having a groove in the internal faceextending along and facing the circumference of the double cone curvedjuncture.
 2. A device according to claim 1, wherein the width of saidgroove approximates the curved portion of the juncture.
 3. A deviceaccording to claim 1, wherein the depth of said groove approximates 75percent of the thickness of the sleeve.
 4. A device according to claim1, wherein said sleeve comprises two half shells providing in assembledcondition a substantially continuous groove adjacent to said curvedjuncture.